Vehicle suspension system

ABSTRACT

A vehicle suspension comprising a frame and a pair of levers carried by the frame on opposite sides thereof. Each lever is pivotally mounted on the frame for swinging movement on an axis intermediate opposite ends of the lever transverse to the frame. The suspension includes a pair of beams, one extending forward from one of the levers and the other extending forward from the other lever, each of the forwardly-extending beams having a pivotal connection with the respective lever forward of the lever axis and having a support for a forward axle. The suspension also includes a pair of beams, one extending rearward from one of the levers and the other extending rearward from the other lever, each of said rearwardly-extending beams having a pivotal connection with the respective lever rearward of the lever axis and having a support for a rearward axle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application No.10/433,124, filed May 22, 2005, entitled VEHICLE SUSPENSION SYSTEM, theentire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to vehicle suspensions, and moreparticularly to an improved suspension for tandem-axle trucks.

The present invention is especially suited for beam-type suspensionswhere the axles of a tandem-axle truck are supported by beams pivoted tohangers on opposite sides of the frame of the truck. Springs (e.g., airbags) on the axle ends of the beams support the frame. Ideally, suchsuspensions are designed to be as lightweight as possible, to provide asoft ride and adequate roll stiffness or stability, that is, resistanceto the tendency of the truck body to roll laterally during cornering, toprovide an even distribution of the load over the wheels as the trucktravels over bumps and as it turns, to provide good braking, to minimizetorque applied to the axle as the vehicle encounters bumps in the road,and as it turns, and to eliminate so-called “dock walk”, which is thetendency of a vehicle to move away from a dock as it is being loaded.While certain prior designs have achieved some of these objectives, ithas usually been at the sacrifice of other objectives. There is a need,therefore, for a suspension which represents an improvement over priorsuspensions.

SUMMARY OF THE INVENTION

The suspension of the present invention is an improvement which isintended to meet most if not all the aforementioned objectives Thesuspension provides a high degree of roll stability and, in someembodiments, substantially eliminates dock walk. The suspension isdesigned to reduce torque on the axle to increase axle life, and ingeneral has components of greater durability The suspension provides asoft ride performance equal to or better than existing air systems. Insome embodiments the suspension provides load equalization under brakingso only one of the two axles requires ABS sensors. The suspension isequipped for easy axle alignment, either at the factory or in the field.The suspension can be used as a tandem road trailer unit withoutmodification. The system is light in weight and can be fabricated at lowcost. Further, the suspension can be used with existing trailers andaxle and brake systems. The suspension is also designed to reduce axlestress so that the axles of the suspension can be made of lightermaterial, if desired.

In one embodiment, a vehicle suspension of this invention comprises aframe for support of a vehicle, the frame having a forward end, arearward end and sides. A pair of levers is carried by the frameintermediate the ends of the frame, one at one side and the other at theother side of the frame. Each lever is pivotally mounted with respect tothe frame for swinging movement on an axis intermediate opposite ends ofthe lever transverse to the frame. The suspension includes a pair ofbeams, one extending forward from one of the levers and the otherextending forward from the other lever. Each of the forwardly-extendingbeams has a pivotal connection with the respective lever forward of thelever axis and has a support for a forward axle. The suspension alsoincludes a pair of beams, one extending rearward from one of the leversand the other extending rearward from the other lever, each of therearwardly-extending beams having a pivotal connection with therespective lever rearward of the lever axis and having a support for arearward axle. A forward pair of springs is provided, each interposedbetween a respective forwardly-extending beam and the frame. A rearwardpair of springs is also provided, each interposed between a respectiverearwardly-extending beam and the frame.

In another embodiment, the suspension comprises a frame for support of avehicle, the frame having a forward end, a rearward end and oppositesides, a pair of rails extending longitudinally of the suspension atopposite sides of the frame, and front and rear hangers depending fromeach rail at locations intermediate the ends of the frame. Thesuspension includes a pair of forwardly-extending beams, one extendingforward from one of the front hangers and the other extending forwardfrom the other front hanger, each of said forwardly-extending beamshaving a pivotal connection with the respective front hanger and havinga support for a forward axle, and a pair of rearwardly-extending beams,one extending rearward from one of the rear hangers and the otherextending rearward from the other rear hanger, each of therearwardly-extending extending beams having a pivotal connection withthe respective rear hanger and having a support for a rearward axle.Each of the pivotal connections between one of the hangers and arespective beam comprises a resilient bushing assembly. A forward pairof springs is interposed between respective forwardly-extending beamsand the frame, and a rearward pair of springs is interposed betweenrespective rearwardly-extending beams and the frame.

Another aspect of this invention is directed to a bushing assembly for apivot connection between a vehicle frame and axle-supporting beam of avehicle suspension to permit pivoting of the beam relative to the frame.The bushing assembly comprises an inner metal sleeve having a centrallongitudinal axis about which the beam is adapted to pivot, and aresilient annular bushing member of resilient material surrounding theinner metal sleeve. The bushing member has a radial inner surfaceadjacent the inner metal sleeve and an opposite radial outer surface. Anouter metal sleeve surrounds the bushing member, the outer metal sleevehaving a radial inner surface adjacent the bushing member and anopposite radial outer surface. The outer surface of the resilientbushing member is relieved in a radially inward direction toward saidcentral longitudinal axis to facilitate deflection of the bushing memberin said radially inward direction.

In another aspect, a vehicle suspension of the present inventioncomprises a frame having opposite sides, and a pair of suspension beamsat opposite sides of the frame, each beam having first and second ends.Each beam is pivotally connected to the frame generally adjacent thefirst end of the beam. An axle support is provided toward the second endof each for supporting an axle on the beam. The support includes a pairof side seat assemblies on opposite sides of the beam. Each side seatassembly comprises first and second seats having opposingaxle-supporting surfaces, and a fastener for drawing the first andsecond seats toward one another to clamp the axle-supporting surfacesagainst the axle. A camshaft bracket and a brake chamber bracket aremounted on the axle support.

Another aspect of the present invention is directed to a vehiclesuspension system comprising a frame having opposite sides, and a pairof suspension beams at opposite sides of the frame each having a pivotalball joint connection at one end thereof with the frame and an axlesupport at the other end thereof.

In another embodiment, a vehicle suspension of the present inventioncomprises a frame having opposite sides, and a pair of suspension beamsat opposite sides of the frame, each beam having first and second ends.A pivotal connection is provided between each beam and the framegenerally adjacent the first end of the beam. The suspension includes anaxle of generally rectangular cross section extending generallytransversely with respect to the frame from one side of the frame to theother, and an axle support on each of the beams toward the second end ofthe beam for supporting the axle on the beam. The axle support includesat least one side seat affixed to the beam at one side of the beam andat least one U-bolt fastener defining an axle-receiving opening, theU-bolt fastener having legs extending through openings in the side seat,and nuts threaded on the legs of the U-bolt fastener to tighten thefastener and thereby clamp the axle in fixed position against the sideseat. The nuts are removable from the at least one U-bolt fastener topermit removal of the axle from the beam.

In another embodiment, a vehicle suspension of the present inventioncomprises a frame having opposite sides and a pair of elongatesuspension beams at opposite sides of the frame. Each beam has oppositesides, opposite ends, a pivotal connection with the frame toward one endof the beam, and an axle support toward the other end thereof. The axlesupport comprises a pair of axle side seats secured to the beam andprojecting laterally outwardly from opposite sides of the beam. The sideseats have axle-supporting surfaces for supporting the axle at locationsoutboard of beam. A mechanism is provided for securing the axle in theoutboard axle side seats.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a first embodiment of a vehicle suspension inwhich the suspension beams are in a push-pull orientation and pivoted toequalizing levers;

FIG. 2 is a side elevation of FIG. 1;

FIG. 3 is a side elevation showing a pair of springs for urging theequalizing lever to a generally horizontal position;

FIG. 4 is an enlarged horizontal section taken in the plane of 4-4 ofFIG. 2;

FIG. 5 is a cross-sectional view showing an alternative bushingconnection between a suspension beam and one end of an equalizing lever;

FIG. 6 is a sectional view similar to FIG. 4 showing ball jointconnections between an equalizing lever and two suspension beams;

FIG. 7 is a perspective of one of the ball joints of FIG. 6;

FIG. 8 is a sectional view of an alternative ball for the ball joints ofFIG. 6;

FIG. 9 is a sectional view similar to FIG. 6 showing eccentric balljoint connections;

FIG. 10 is a perspective of one of the ball joints of FIG. 9;

FIG. 11 is a sectional view of the ball joint of FIG. 9;

FIG. 12 is an exploded view of the ball joint of FIG. 9;

FIG. 13 is a top perspective of an axle support on a suspension beam;

FIG. 14 is a top plan view of the axle support and beam of FIG. 13;

FIGS. 15-18 are sectional views taken on in the planes of lines 15-15,16-16, 17-17 and 18-18, respectively, on FIG. 14;

FIG. 19 is a perspective view similar to FIG. 13 but without the axleand showing certain parts exploded to illustrate details of the axlesupport;

FIG. 20 is an enlarged perspective of a portion of FIG. 19 showingfeatures of the axle support;

FIG. 21 is a top perspective showing an alternative axle support;

FIG. 22 is a bottom perspective of the axle support of FIG. 21;

FIG. 23 is another top perspective of the axle support of FIG. 21, takenfrom a different vantage point;

FIG. 24 is another bottom perspective of the axle support of FIG. 21,taken from a different vantage point;

FIG. 25 is a perspective view of the assembly of FIG. 21 turned upsidedown and with the axle removed to better illustrate the axle support;

FIG. 26 is a schematic view showing the axle support area of the designof FIG. 21;

FIG. 27 is a schematic view showing the axle support area of a prior artdesign;

FIG. 28 is a perspective of another embodiment of the suspension inwhich the equalizing levers are eliminated and in which the suspensionbeams at each side of the frame are pivoted on hangers and connected bya spacer bar for maintaining the distance between the pivot pointsfixed;

FIG. 29 is a side elevation of the suspension of FIG. 28;

FIG. 30 is an enlarged section taken in the plane of line 30-30 of FIG.29 showing bushing assemblies for pivotally connecting the suspensionbeams to the hangers;

FIG. 31 is a perspective bushing member of a bushing assembly of FIG.30;

FIG. 32 is a top plan view of the bushing member of FIG. 31;

FIG. 33 is an end elevation of the bushing member;

FIG. 34 is a sectional view taken in the plane of line 34-34 of FIG. 33;

FIG. 35 is a sectional view taken in the plane of line 35-35 of FIG. 32;

FIG. 36 is a view similar to FIG. 35 showing the bushing memberassembled with an outer sleeve;

FIG. 37 is a top perspective of an axle support for supporting an axleof rectangular cross section on a suspension beam;

FIG. 38 is a side elevation of the axle support of FIG. 37;

FIG. 39 is a top plan of FIG. 37;

FIG. 40 is a right end view of the axle support of FIG. 37;

FIG. 41 is a sectional view taken in the plane of line 41-41 of FIG. 39;

FIG. 42 is a bottom perspective of a suspension beam and axle supportwith a brake chamber bracket and camshaft bearing bracket mounted on theaxle support;

FIG. 43 is a top perspective of the suspension beam and axle support ofFIG. 42;

FIG. 44 is a top perspective of another embodiment of a suspension beamand axle support with a brake chamber bracket and camshaft bearingbracket mounted on the support; and

FIG. 45 is a bottom perspective of the suspension beam and axle supportof FIG. 44.

Corresponding parts are designated by corresponding reference numeralsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1-4 of the drawings, a vehicle suspension of thepresent invention is designated in its entirety the reference numeral 1.As shown, the suspension is a slider of the type which is affixed to theframe of truck. However, it will be understood that the presentinvention has applications to vehicle suspensions generally.

The suspension comprises a frame 3 which includes a pair of parallelrails 5 connected by cross members 7, and hangers 9 depending from therails 5 at opposite sides of the frame generally midway between the endsof the rails. The frame has forward and rearward ends, the forward endbeing the left end as viewed in FIG. 1 and the rearward end being theopposite (right) end. In accordance with one aspect of the presentinvention, the frame further comprises a pair of levers 11, referred toas equalizers, one at one side of the frame 3 and the other at the otherside of the frame. Each lever 11 (comprising two parallel bars 11 a, 11bin the embodiment shown in FIGS. 1-4) has a pivot connection, generallydesignated 15, with a respective hanger 9 for swinging movement on agenerally horizontal axis 16 intermediate opposite ends of the levertransverse to the frame. The frame also includes a pair of suspensionbeams 17 extending forward from one end of the levers 11, and a pair ofsuspension beams 19 extending rearward from the other end of the levers.Each of the forward-extending beams 17 has a pivot connection 23 withthe respective lever forward of the lever pivot connection 15 andfurther supports a forward axle 27 Each of the rearward-extending beams19 has a pivot connection 29 with the respective lever 11 rearward ofthe lever pivot connection 15 and supports a rearward axle 33 A forwardpair of springs 3S (e.g., air bags) is interposed between respectiveforward-extending beams 17 and the frame 3, and a rearward pair ofsprings 37 (e.g., air bags) is interposed between respectiverearward-extending beams 19 and the frame 3 The forward and rearwardbeams 17, 19 carry axle supports, each generally designated 41, forsupporting the respective axles on the beams.

The levers 11 function to permit the suspension beams 17, 19 to moveessentially independently of one another, so that the loading on thewheels of the vehicle is maintained substantially uniform as the vehiclemoves over bumps in the road and as the vehicle turns. The suspensionprovides good roll stability or stiffness, i.e., resistance to rolloverduring cornering, and minimizes axle torque, especially during travelover bumps, potholes and the like. For efficient operation, the levers11 are maintained in a generally horizontal position by the resilientnature of the pivot connections 15, as will be described, although othermeans may be used, e.g., coil compression springs 45 (FIG. 3), rubbersprings, or linkages.

In the embodiment illustrated in FIGS. 1-4, each hanger 9 comprises apair of parallel generally triangular spaced apart metal plates 51affixed (e.g., welded) to a respective rail 5 of the frame. The hangerplates 51 are reinforced along their sides by stiffening flanges 53 andat their bottoms by reinforcing plates 55 welded thereto (see FIG. 4).The equalizing lever 11 at each side of the frame is preferably disposedbetween the two hanger plates 51 of a respective hanger adjacent thelower ends of the plates.

The pivot connection 15 between the equalizing lever 11 and the hanger 9at each side of the frame is shown in FIG. 4 as comprising a bushingassembly generally designated 59 having inner and outer sleeves 61, 63and a tubular bushing member 65 of resilient material (e.g., rubberhaving a Shore A durometer preferably in the range of 65-75 and morepreferably about 70) between the sleeves, all three components beingconcentric with the pivot axis 16. The outer sleeve 63 is received inaligned holes in the two equalizer bars 11 a, 11 b and is immovablyaffixed to the bars, as by welding. The outer sleeve 63 is somewhatshorter (e.g., 0.062 in.) than the inner sleeve 61, for reasons whichwill become apparent. The resilient bushing member 65 has a press(frictional) fit with the inner and outer sleeves 61, 63 to preventrelative rotation between the inner surface of the bushing member andthe inner sleeve and between the outer surface of the bushing and theouter sleeve. The resiliency of the bushing material itself allowslimited relative rotational and angular movement between the inner andouter sleeves 61, 63, “angular” meaning movement of the axes of the twosleeves out of parallelism. A pivot bolt 71 extending through the innersleeve 61 and through aligned openings 73 in the hanger plates 51 andaligned openings 75 in the reinforcing plates 55 is held in place by anut 77 threaded up on the bolt. Conventional washers 79 are provided onthe bolt 71 between the hanger plates 51 and the head of the bolt andthe nut 73. Hardened 81 washers are disposed between the ends of thebushing assembly 59 and the reinforcing plates 55 of the hanger. Whenthe nut 77 is tightened on the pivot bolt 71, the hardened washers 81and inner sleeve 61 of the bushing assembly are clamped in fixed(non-rotatable) position. Since the outer sleeve 63 is shorter than theinner sleeve 61, it is free to rotate to the extent permitted by theflexing of the resilient bushing member 65. This rotation occurs as theequalizing lever 11 pivots on the pivot bolt 71 in response to up anddown movement of the suspension beams 17, 19 to equalize the forces onthe axles 27, 33 carried by the beams. The resilience of the bushingmember 65 urges the lever 11 back toward a neutral (horizontal)position.

It will be noted that the openings 73, 75 in the hanger plates 51 andreinforcing plates 51, 55 are clearance openings substantially larger indiameter than the diameter of the pivot bolt 71. This allows for foreand aft adjustment of the equalizing lever 11 and associated beams 17,19 to permit adjustment of the respective ends of the axles carried bythe beams to attain precise alignment of the axles transversely of thevehicle. (When properly aligned, the front and rear axles carried by thesuspension beams should be parallel to one another and perpendicular tothe longitudinal centerline of the trailer, typically extending throughthe kingpin of the vehicle.) After the position of each lever 11 isadjusted to achieve proper axle alignment, the nuts 77 are tightened onthe pivot bolts 71 to lock the equalizing levers 11 in fixed positionrelative to respective hangers 9. If desired, the pivot bolt washers 77(which have a close clearance fit with the pivot bolt) can also bewelded to respective hanger plates 51 to further insure that theequalizer remains in proper position to maintain axle alignment.

The construction of the pivot connections 23, 29 between the levers andthe beams 17 is also shown in FIG. 4. As illustrated, each such pivotconnection 23, 29 comprises a bushing assembly generally designated 85disposed between the two bars 11 a, 11 b of the equalizing lever 11adjacent an end of the lever. The bushing assembly 85 comprisesconcentric inner and outer sleeves 87, 89 surrounding a cylindricalresilient bushing member 91 having a press (frictional) fit with bothsleeves. In one embodiment, the bushing member is of rubber preferablyhaving a 65-75 Shore A durometer, and more preferably about a 70 Shore Adurometer. The outer sleeve 89 of the bushing assembly is affixed (e.g.,welded) to a respective beam 17, 19. The assembly 85 is held in place bya pivot bolt 95 extending through the inner sleeve 87 and aligned holesin the lever bars 11 a, 11 b, and a nut 99 threaded up on the boltagainst one of the bars. Hardened metal washers 101 are provided betweenthe ends of the inner sleeve 87 and the lever bars. When the nut 99 istightened, the inner sleeve 87 and washers 101 are clamped in fixed(non-rotating) position relative to the lever bars 11 a, 11 b. The outersleeve 89 is somewhat shorter than the inner sleeve 87 to provide gapsbetween the ends of the sleeve and the washers. The resilience of thebushing member 91 provides limited rotational and angular movementbetween the inner and outer sleeves 87, 89 of the bushing assembly topermit limited pivotal and angular movement between the respective beam17, 19 and the lever 11. Angular movement of the outer sleeve 89relative to the inner sleeve 87 of the bushing (caused by jackknifeforces exerted on the beam) is limited by contact between the ends ofthe outer sleeve 89 and the hardened washers 101. The ends of thebushing member 91 are tapered to prevent undue rubbing of the bushingmember against the washers 101.

It will be observed from the foregoing that the suspension beams 17, 19are arranged in a push-pull orientation, that is, the forward beams arepushed forward and the rearward beams are pulled forward as the vehiclemoves along the road. This arrangement eliminates the “dock walk”problem suffered by many conventional air-ride suspensions. Further, theuse of the equalizing levers 11 equalizes the load between the wheels ofthe vehicle, thereby reducing axle torque while providing good rollstability. The pivot connections 23, 29 between the suspension beams andthe hangers 9 reduce the number of parts used in conventional designs,thus allowing for a reduction in weight of the suspension and reducingwear.

While the suspension of the present invention is applicable to air-ridesuspensions, it will be understood that any type of spring element maybe used in lieu of an air bag. For example, the air springs are replacedby rubber springs of the type commercially available from TimbrenIndustries Inc. of Niagara Falls, N.Y., Model Aeon® 570 Rubber Springsupport. Also, it will be understood that an equalizing lever of thepresent invention could comprise a single bar or the like pivotallymounted to a hanger. Similarly, the hangers, beams and other componentsof the suspension 1 could take other forms.

FIG. 5 shows an alternative bushing assembly 105 for use in a connectionbetween a flange 106 and a beam or between a lever (not shown) and abeam 17, 19. In this embodiment, interlocking ribs 107, 109 are formedon the inner surface of the outer sleeve 111 and on the outer surface ofthe bushing member 113 to prevent axial slippage between the two parts.The friction lock provided by these ribs 107, 109 should be sufficientto withstand the maximum lateral loads (e.g., 8000 lbs) applied to theaxle during cornering of the vehicle. The ribs 107 on the outer sleeve111 can be formed by machining the sleeve, or by roll forming. Further,the interference fit between the bushing member 113 and the outer sleeve111 can be provided by means other than interlocking ribs.

FIGS. 6-8 illustrate a third embodiment of a pivot connection, generallydesignated 121, between a lever 11 and a beam 17, 19. In thisembodiment, the pivot connection 121 comprises a ball joint designatedin its entirety by the reference numeral 125. The ball joint comprises ahollow open-ended housing, and more particularly a cylindrical sleeve127, e.g. a steel sleeve, extending transversely of the beam 17, 19 atits pivot end, secured thereto as by welding at 129. Inserted in thesleeve are two annular bushings 131, which may be made of powdered metal(sintered). Each bushing 131 has a part-spherical cavity such asindicated at 135 and an opening 137 in the outside thereof extendingfrom its outside to the cavity. The bushings 131 are fitted tightly inthe sleeve 127 with their inner sides engaging one another, defining apart-spherical ball seat. A ball 141, made of steel, for example, isrotatably seated in the seat (before the bushings are inserted in thesleeve). The ball 141 has two aligned tubular projections eachdesignated 143 at opposite sides thereof which extend radially outwardto some extent through the openings 137 in the bushings 131. A bore 145through these projections, which may be termed “trunnions”, and throughthe ball 141 define a transverse hole for a bolt 151. The bushings 131;135 are held in the sleeve 127 by c-clips 155 snapped into internalannular grooves in the sleeve. In the ball joint 125, the bushings 131,the ball 141, and the tubular projections or trunnions 143 are coaxialwith the sleeve 127, the axis thereof (indicated at A-A in FIG. 6) beingdiametrical with respect to the ball seat and the ball 141, andextending centrally through the hole 145. The pivot bolt 151 and a nut161 thereon hold the ball joint in position with the ends of thetrunnions 143 clamped immovably against respective bars 11 a, 11 b ofthe equalizing lever. The ball joints 125 allow relative pivotalmovement between the beams 17, 19 and the equalizing lever 11, both in avertical plane and laterally with respect to this plane (to a limitedextent).

FIG. 8 shows an alternative design where the ball 165 of the ball jointis hollow, as indicated at 167. In this embodiment, the center of thehollow 167 is preferably aligned with the axis A-A of the tubularprojections 169.

FIGS. 9-12 illustrate a modification of the ball joint, designated 125 ain its entirety, having parts generally corresponding to those of balljoint 125 and designated by the same reference numerals as used for balljoint 125 with the subscript a (e. g. sleeve 127 a). The modification125 a differs from 125 primarily in that the tubular projections ortrunnions 143 a (143 in ball joint 125) are on an axis Aa-Aa offset inrelation to the diameter A-A of the ball shown in FIG. 11, and in thatis formed with flats 175 (FIG. 10) on each of the tubular projections ortrunnions 143 a for application of a wrench for turning the ball 141 arelative to the ball seat formed by the bushings 131 a. The bolt hole145 a in the ball 141 a and trunnions 143 a is on axis A-A, which isoffset (eccentric) with respect to the center line of the trunnions(which is line Aa-Aa as shown in FIG. 11. The arrangement, with the ball141 a thus mounted eccentrically in the seat to the extent indicated atE in FIG. 11, allows for fore and aft adjustment of the beam 17, 19 onwhich the ball joint is mounted for fore and aft adjustment of therespective end of the axle carried by the beam to attain precisealignment of the axle transversely of the vehicle.

Referring to FIGS. 13-20, each axle support 41 comprises a pair of sideseats each generally designated 201 on opposite sides of a respectivebeam 23, 29 intermediate the ends of the beam. In one embodiment, theside seats 201 are integral steel castings each having a generallyvertical leg 205 affixed (e.g., welded) to a respective side wall 207 ofthe beam, and a generally horizontal leg 209 having an outboard section211 extending laterally outboard of the beam and an inboard section 213extending laterally inboard of the beam, the inner edges of the twoinboard sections being relatively closely spaced over the top wall 217of the beam. The generally horizontal leg 209 of each side seat 201 hasan axle-supporting surface 221, preferably contoured (e.g., rounded) tomatch the contour of the axle 27, 33. The axle 27, 33 is immovably heldon these axle-supporting surfaces 221 by suitable fasteners, such as apair of U-bolts 241 having threaded ends which extend down through holes243 in the outboard sections 211 of the side seats, and nuts 245tightened up on the U-bolts. Washers 247 are provided between the nutsand the undersides of the castings. The axle is thus supported by theseside seats 201 at locations outboard of the beam on opposite sides ofthe beam, thereby reducing the bending stresses on the axle compared toprior designs where the axle is supported more inboard with respect tothe beam. Significantly, the axle is not welded to the side seats 201,at least in the embodiment shown in FIGS. 13-20, thereby avoiding stressrisers in the axle at these locations. The U-bolts 241 may be of thetype which can be tightened and loosened, or lockbolts which, oncetightened, remain permanently secured. Suitable lockbolts arecommercially available from Huck International Inc. of Waco Tex. underthe trademark “U-Spin”. Other types of U-bolts or mechanical fastenersmay be used.

Referring again to FIGS. 13-20, the axle support 41 preferably furthercomprises a center axle seat 251 bridging the two side seats 201generally between opposite sides 207 of the beam. In one embodiment (seeFIGS. 19 and 20), the center seat 251 comprises a one-piece memberformed from metal plate having a pair of end sections 251 a connected bya center section 251 b of reduced width, thereby providing fourshoulders 255 at the corners of the member, the shoulders being receivedin notches 257 in the side seats. The center seat 251 has an axlesupporting surface 261, also contoured to match the contour of the axle.By way of example, and not limitation, the center seat may be a stampedsteel plate having a thickness of about 0.31 in. The center seat sitsdown in recesses 265 formed in the inboard sections 213 of the sideseats 201 so that the axle-supporting surface 261 of the center seat isflush with the axle-supporting surfaces of the 211 of the side seats, asshown best in FIG. 18. The center seat 251 is preferably welded to theinboard sections 213 of the side seats 201, as indicated in FIG. 13.

FIGS. 18-20 illustrate the steps involved in assembling the center andside seats 209, 251. FIG. 20 shows the center seat 251 in place prior toinstallation of the axle, the shoulders 255 of the center seat beingreceived in the notches 257 in the side seats 201. After installing andtightening the U-bolts 241 (FIG. 18), the axle-supporting surface 261 ofthe center seat should have a curvature and be at a level which closelycoincides with the curvature and level of the axle-supporting surfaces221 of the side seats 201. To provide additional resistance againstrotation of the axle 27, 33 relative to the beam 25, 29, the axle ispreferably rigidly affixed to the center seat 251, as by a suitableadhesive, such as an anaerobic adhesive made by Locktite Corporationproviding a shear strength of 4,000 psi. The use of adhesive isadvantageous over welding, for example, because it avoids stress risersin the axle, thereby allowing the axle to be made of lighter (e.g.,thinner wall) tubing.

In the embodiment of FIGS. 13-20, the side and center seats 201, 251combine to support the axle over a greater length of the axle (comparedto prior art designs), thereby reducing axle stress. However, it iscontemplated that the side seats 201 may be used without the center seat251. Further, the side seats 201 may have configurations other than asshown in the drawings. For example, one or both of the inboard sections213 of the side seats could be eliminated. Also, the outboard section211 of one of the seats 201 could be eliminated. Further, the axle canbe adhesively secured to the axle-supporting surfaces 221 of the sideseats 201, regardless of the presence of a center seat 251.

While the axle supports 41 described above support the axles 27, 33above the beam 17, 19, the same supports 41 can be used to support theaxles under the beam in an underslung fashion, as will be understood bythose skilled in this field.

FIGS. 21-25 illustrate an alternative axle support, generally designated301, supporting an axle 27, 33 below the bottom wall 281 of a suspensionbeam 17, 19. The support 301 is generally similar to axle support 41 inthat it comprises a pair of side seats, each designated 305 and eachhaving axle-supporting surfaces 307 contoured to match the shape of theaxle. The side seats 305 extend laterally outboard of the beam onopposite sides of the beam. U-bolts 309 or other mechanical fastenersclamp the axle in place. The support 301 also has a center seat,generally designated 311, but of different construction than the centerseat 251 of axle support 41. In this embodiment, the center seat 311comprises two inboard seat members 313 formed (in one embodiment) byintegral extensions of the side seats 305, similar to two inboard sideseat sections 213 of axle support 41, but without the recesses 265. Theinboard seat members 313 have axle-supporting surfaces 315 (FIG. 25)contoured to match the shape of the axle. In one embodiment, theaxle-supporting surfaces 307, 315 of a side seat 305 and its adjacentinboard seat member 313 combine to provide a continuous uninterruptedarea for supporting the axle, as shown best in FIG. 25. Each center seatmember 313 is preferably formed as an integral part of a respective sideseat member 305, but it will be understood that they could be formed asseparate parts, with the center seat members being attached to the beam,for example. Also, the center seat members 313 could be formed as asingle one-piece casting, for example. Regardless of how the center seatmembers 313 are constructed, it is preferable that the axle be welded tothe center seat members, as indicated at 321 in the drawings (e.g.,FIGS. 22 and 23), to assist in holding the axle against rotation. Thestress risers in the axle caused by these welds are minimized because ofthe location of the welds generally inboard of the sides of the beam andbetween the two U-bolts 309.

Axle support 301 can be used to support an axle above a suspension beamas well as below the beam.

Like axle support 41, axle support 301 is advantageous for variousreasons. For example, compared to prior axle supports, the extension ofthe area of axle support to locations outboard of the beam, and evenoutboard of the U-bolts, increases the area of axle support anddecreases the bending stresses on the axle. This is best illustrated bycomparing FIG. 26, schematically representing axle support 301, and FIG.27 schematically representing a conventional axle support, generallydesignated 331. The areas providing axle support are shaded in bothFigures. It is apparent that the area provided by support 301 issubstantially greater, since the support extends outboard of the beamand thus has a relatively large overall dimension D1 in a directiontaken transverse to the centerline of the vehicle. In contrast, theprior art support 301 provides support inboard of the beam only, and hasan overall transverse dimension D2 less than D1. (By way of example, D1may be in the range of 10-12 in., whereas D2 is typically in the rangeof 5-8 in.) As a result, the bending stresses on the axle are reducedsignificantly when support 301 is used, which enables the axle to bemade of lighter construction (e.g., reduced wall thickness).

FIGS. 28-30 illustrate another embodiment of the suspension, generallyindicated at 351, in which the forward suspension beams 353 and rearwardsuspension beams 355 are connected to forward and rearward hangersdesignated 357 and 359, respectively, at each side of the frame. Asshown in FIG. 30, the forward hanger 357 comprises a vertically orientedchannel-shaped hanger member having a pair of generally parallel sidewalls 365 and a connecting wall 367 joining the side walls at the rearedges of the side walls. The rearward hanger 359 comprises a similarvertically oriented channel-shaped hanger member having a pair ofgenerally parallel side walls 371 and a connecting wall 373 joining theside walls at the front edges of the side walls, the connecting walls367, 373 of the two hangers preferably being spaced from one another.Each beam 353, 355 has a pivot connection 375 with a respective hangermember. This connection 375 comprises a bushing assembly, generallydesignated 379, a pivot bolt 381 passing through the bushing assembly379 and through horizontal slots 385 in the side walls 365, 371 ofrespective hangers, a first pair of hardened wear washers 387 on thebolt 381 between the ends of the bushing assembly 379 and the side wallsof the hangers, and a second pair of washers 391 on the bolts betweenthe heads of the bolts and the side walls of the hangers. The slots 385in the side walls of the hangers 357, 359 permit the position of eachbeam relative to its respective hanger to be adjusted inforward-to-rearward direction to insure that the axle clamped to thebeam is perpendicular to the longitudinal centerline of the frame andvehicle. Once adjusted, the position of the beam 353, 355 is fixed bytightening a nut 395 on the bolt. The distance D between the pivotconnections 375 of the forward and rearward beams to their respectivehangers at each side of the frame is maintained fixed by a pair ofspacer bars 399 having holes 401 therein for receiving the two bolts381. The spacing D between the bolts 381 at one side of the frame isabout equal to the spacing D between the bolts at the opposite side ofthe frame, so that the axles are maintained parallel.

Referring to FIGS. 30-36, the bushing assembly 379 comprises an innermetal sleeve 405 having a central longitudinal axis 407 about which thebeam 353, 355 is adapted to pivot, and a cylindrical bushing member 411of resilient material (e.g., molded rubber) surrounding the inner metalsleeve 405 and having a press (friction) fit thereon. The bushing member411 has a radial Inner surface 413 adjacent the inner metal sleeve 405and an opposite radial outer surface 415 (FIG. 34). The bushing member411 is press fit inside an outer metal sleeve 417 which surrounds thebushing member. The outer metal sleeve 417 has a radial inner surface421 adjacent the bushing member 411 and an opposite radial outer surface423 (FIG. 36). As shown in FIGS. 31-36, which illustrate the bushingmember in its installed orientation on a vehicle, one or more regions ofthe outer surface 415 of the resilient bushing member 411 are relievedin a radially inward, generally vertical direction. That is, thevertical radial dimension of the bushing member is reduced in theseregions to facilitate compression of the bushing member in the verticaldirection (and thus vertical movement of the beam 353, 355 relative toits respective hanger 357, 359). The bushing member 411 is notsubstantially relieved in the horizontal direction, thereby maintainingthe stiffness of the bushing member in a direction extending generallylongitudinally with respect to the vehicle. In the embodiment shown, theouter surface of the bushing member 411 has an unrelieved cylindricalregion 431 between opposite ends of the bushing member, and a pair ofrelieved regions 433 formed by generally wedge-shaped recesses onopposite sides of the unrelieved region 431 toward opposite ends of thebushing member. This end-relief configuration facilitates angularrocking movement of the inner sleeve 405 relative to the outer sleeve asis apparent from FIG. 36, “angular” movement being movement of the twosleeves out of parallel to a position in which the axes of the twosleeves are skewed relative to one another. In one preferred form (FIG.36), the relieved regions 433 have combined axial lengths L1 greaterthan the axial length L2 of the unrelieved region 431, and each relievedregion curves generally radially inward and axially toward a respectiveend of the bushing member 411. The bushing member 411 is preferablyconfigured so that when it is pressed in place between the inner andouter sleeves 405, 417, the ends of the bushing member are generallyflush (co-planar) with the ends of the inner sleeve 405. By way ofexample, referring to FIG. 34, the bushing member 411 may be configuredto have ends tapered at an angle Θ (about 30 degrees in one embodiment)prior to assembly with the outer sleeve 417. During assembly, e.g., asthe member 411 and outer sleeve 417 are press fit together, the member411 deforms to assume a final configuration wherein the ends of thebushing member are generally flush with the inner sleeve. As inpreviously described embodiments, the outer sleeve 417 is somewhatshorter than the inner sleeve 405 so that when the pivot bolt 381 istightened, the inner sleeve is clamped fixedly in place while the outersleeve is allowed to rotate to a limited extent (as permitted by theflexibility of the bushing member 411) to accommodate pivoting of thebeam 353, 355. Angular movement of the outer sleeve (and beam) relativeto the inner sleeve (and hanger) is restricted by engagement of the endsof the outer sleeve 417 with the hardened washers 387.

By way of example, but not limitation, the unrelieved region 431 of theinstalled bushing member 411 shown in FIG. 36, may have an axial lengthL2 of about 2.0 in., and the combined axial lengths L1 of the relievedregions 433 may be about 3.0 in., providing an overall bushing memberlength of about 5.0 in., which generally corresponds to the length ofthe inner metal sleeve 405. Further, the cylindrical unrelieved region431 of the bushing member 411 may have an outside diameter of about4.375 in. and an inside diameter of about 2.0 in. The relieved regions433 may have an outside diameter OD at the ends of the bushing member ofabout 3.75 in., an inside diameter ID of about 2.0 in., and a radius ofcurvature of about 1.0 in (see FIG. 36). The outer sleeve 417 may havean overall length about 0.250 in. less than the inner sleeve 405.

The design of bushing assembly 379 is advantageous in that the verticalradial relief of the bushing member 411 enables greater deflection ofthe bushing member under a given vertical load while maintaining bushingstiffness under generally horizontal loads (i:e., loads in the generallylongitudinal direction with respect to the vehicle). This design reducesthe need for axle realignment and yet provides for good roll stiffnessof the vehicle. It will be understood that the specific relievedconfiguration of the bushing member 411 can change without departingfrom the scope of this invention.

FIGS. 37-41 illustrate an axle support of the present invention,generally designated 451, for use with an axle 453 of generallyrectangular (e.g., square) cross section. The axle 453 may be solid ortubular and has four generally flat sides 455 and four rounded corners457. The support 451 includes at least one side seat 461, and preferablytwo side seats 461 on opposite sides of the beam 17, 19. These seats 461are similar to the side seats 305 of axle support 301 except that eachseat 461 has an axle-supporting surface 465 contoured to fit the contourof the rectangular axle 453. In one embodiment, the axle-supportingsurface 465 of each seat 461 extends on three sides of the axle,corresponding to one side 455 and two adjacent corners 457 of the axle(see FIGS. 38 and 41). The axle 453 is supported on each side seat 461by a U-bolt fastener 467 having legs extending up through openings 471in the generally horizontal legs 475 of the side seats 461, and nuts 481threaded on the legs of the U-bolt fastener to tighten the fastener andthereby clamp the axle against rotational and axial movement relative tothe beam. No welding of the axle to the seat 461 is necessary, providedthe axle-supporting surface 465 extends around at least two corners 457of the axle when the axle is clamped tight against the seat. As a resultof this construction, the axle may be readily removed from the beamsimply by removing the U-bolt fasteners 467. The side seats 461 aresuitably reinforced, as by gussets and reinforcing ribs.

In the embodiment just described, the axle support 451 does not have acenter seat, but it will be understood that a center seat can beprovided, if desired. Also, as with the prior embodiments, it will beunderstood that the axle support 451 can be used for supporting an axleabove or below the suspension beam.

FIGS. 42 and 43 illustrate another axle support, generally designated501, for supporting a rectangular axle (not shown) on a suspension beam503. The support 501 includes at least one side seat assembly 505 on oneside of the beam, and preferably two side seat assemblies 505 onopposite sides of the beam, two such assemblies being shown in FIGS. 42and 43. Each seat assembly 505 includes first and second opposing seatsdesignated 509 and 511, respectively, the first seat 509 being a fixedupper seat in one embodiment and the second seat 511 being a lowermovable seat. The upper fixed seat 509 has a generally vertical leg 515affixed (as by bolted connections or by welding) to a respective side ofthe suspension beam 503, and a generally horizontal leg 517 extendinglaterally out from the beam. The lower movable seat 517 is spaced belowthe generally horizontal leg 517 of the upper seat 509. The seats 509,511 have opposing axle-supporting surfaces 521, each of which ispreferably contoured to match the shape of the axle. For example, in oneembodiment each axle-supporting surface 521 is contoured to extend onone side of a rectangular axle and around two adjacent corners of theaxle. Fasteners 525 (e.g., nut and bolt fasteners) are used to draw theupper and lower seats 509, 511 toward one another to clamp a respectiveaxle therebetween against the axle-supporting surfaces 521 of the twoseats. The fasteners can be of the type which can be tightened orloosened, or lock fasteners of the type which, once tightened, remainpermanently secured.

It will be understood that the axle support 501 can also be used tosupport an axle above a suspension beam, in which case the movable seat511 will be above the fixed seat 509. Further, the axle support 501 maybe used to support an axle having any cross-sectional shape, so long asthe axle-supporting surfaces 521 on opposing seats are configured tomatch the contour of the axle.

Again referring to FIGS. 42 and 43, a camshaft bearing bracket 531 formounting the camshaft bearing (not shown) is affixed, as by welding, toa fixed upper seat 509 of one of the side seat assemblies 505. In oneembodiment, the bracket 531 is generally C-shaped and is secured to agenerally downwardly facing surface 533 on the upper seat 509 adjacentthe axle-supporting surface 521. Further, a separate brake chamberbracket 537 is secured to the movable lower seats 511 of the two sideseat assemblies 505. In the particular embodiment shown, the brakechamber bracket 537 is generally L-shaped, having generally vertical andhorizontal legs. The bracket 537 is secured in place by the fasteners525 and is used to mount.the brake chamber (not shown) in a position inwhich the push rod of the brake chamber, when extended by actuation ofthe brake pedal, moves to rotate the camshaft in the camshaft bearing.Such rotation causes a conventional S-cam on the camshaft to push thebrake shoes against the drum of the wheel to brake the wheel, as will beunderstood by those in this field. In conventional designs, the brakechamber bracket 537 and camshaft bearing bracket 531 are welded directlyto the axle, causing stress risers in the axle. The present designeliminates the need to weld these brackets to the axle.

FIGS. 44 and 45 illustrate another axle support, generally designated601, for supporting an axle 603, shown in this embodiment asrectangular, although it will be understood that the axle could haveother shapes (e.g., circular). The support 601 is elongate and extendsthrough the side walls of a suspension beam 607 in a position whereinthe support 601 projects laterally outward from opposite sides of thebeam. The support 601 comprises upper and lower channel members 609, 611which surround the axle 603 and hold it in fixed position. This may beaccomplished, in one embodiment, by welding a first of the two channelmembers (e g., 609) to the beam 607, positioning the axle 603 in thefirst channel member, positioning the second channel member (e.g., 611)on the axle, drawing the two channel member together to clamp the axletherebetween, welding the two channel members 609, 611 together alongtheir adjacent edges, as indicated at 615, and welding the secondchannel member to the beam 607. This procedure has the benefit ofminimizing any direct welds to the axle. Alternatively, the axle can bewelded to one or both channel members 609, 611.

As shown in FIGS. 44 and 45, a brake chamber bracket 621 is held by apair of arms 623 affixed to the lower channel member 611 at one side ofthe beam, and a camshaft bearing bracket 625 is affixed to the upper andlower channel members 609, 611 on the opposite side of the beam..Similar to axle support 501, this arrangement avoids welding eitherbracket 621, 625 to the axle.

The axle support designs described above have several advantages,including the elimination of welding of certain parts to the axles, andthe reduction in bending stresses on the axles.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A bushing assembly for a pivot connection between a vehicle frame andaxle-supporting beam of a vehicle suspension to permit pivoting of thebeam relative to the frame, the bushing assembly comprising: an innermetal sleeve having a central longitudinal axis about which a beam isadapted to pivot; a resilient annular bushing member of resilientmaterial surrounding the inner metal sleeve, the bushing member having aradial inner surface adjacent the inner metal sleeve and a radial outersurface; and an outer metal sleeve surrounding the bushing member, theouter metal sleeve having a radial inner surface adjacent the bushingmember and a radial outer surface, the outer surface of the resilientbushing member being relieved in a radially inward direction toward thecentral longitudinal axis to facilitate deflection of the bushing memberin the radially inward direction.
 2. A bushing assembly as set forth inclaim 1, wherein the outer surface of the bushing member is relievedradially inward at locations adjacent ends of the bushing member tofacilitate angular movement of the inner sleeve relative to the outersleeve to a position in which the axes of the two sleeves are skewedrelative to one another.
 3. A bushing assembly as set forth in claim 2,wherein the outer surface of the bushing member has an unrelievedaxially-extending region between opposite ends of the bushing member,and relieved regions on opposite sides of the unrelieved region.
 4. Abushing assembly as set forth in claim 3, wherein the relieved regionshave combined axial lengths greater than the axial length of theunrelieved region.
 5. A bushing assembly as set forth in claim 3,wherein each relieved region curves generally radially inward andaxially toward a respective end of the bushing member.
 6. A bushingassembly as set forth in claim 5, wherein the bushing member has a pressfit on the inner sleeve and the outer sleeve has a press fit on thebushing member, and wherein the bushing member has opposite ends whichare generally coplanar with respective ends of the inner sleeve.
 7. Abushing assembly as set forth in claim 5, wherein each relieved regioncurves generally radially inward and axially toward a respective end ofthe bushing member.
 8. A bushing assembly as set forth in claim 1,wherein the outer surface of the bushing member has an unrelievedaxially-extending region between opposite ends of the bushing member,and relieved regions on opposite sides of the unrelieved region.